SQL queries can extend to any complexity with additional clauses, sub queries, UNION, and so on. You can make a query that is many pages long. There are also stored procedures and triggers in most implementations of SQL , which introduces functions, conditionals, loops, variables, exception handling, packages, etc. In other words, SQL is a full-blown programming language.

SQL is a programming language like any other. While the basic commands like select, insert, update are easy to comprehend, its the stuff around them that makes it a bit more difficult.